U.S. patent number 10,837,374 [Application Number 15/780,944] was granted by the patent office on 2020-11-17 for characterizing a mixed fuel flow period.
This patent grant is currently assigned to Micro Motion, Inc.. The grantee listed for this patent is Micro Motion, Inc.. Invention is credited to Taylor Robert Scott, Patrick John Zimmer.
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United States Patent |
10,837,374 |
Zimmer , et al. |
November 17, 2020 |
**Please see images for:
( Certificate of Correction ) ** |
Characterizing a mixed fuel flow period
Abstract
A method of characterizing a mixed fuel flow period is provided.
The method includes flowing a mixed fuel, the mixed fuel being
comprised of at least a first fuel type and a second fuel type, the
mixed fuel flow period being determined where the fuel is switched
from the first fuel type to the second fuel type, determining a
density of the first fuel type and a density of the second fuel
type, and determining a total flow, the total flow being determined
from the density of the first fuel type and the density of the
second fuel type.
Inventors: |
Zimmer; Patrick John (Denver,
CO), Scott; Taylor Robert (Boulder, CO) |
Applicant: |
Name |
City |
State |
Country |
Type |
Micro Motion, Inc. |
Boulder |
CO |
US |
|
|
Assignee: |
Micro Motion, Inc. (Boulder,
CO)
|
Family
ID: |
55174730 |
Appl.
No.: |
15/780,944 |
Filed: |
January 6, 2016 |
PCT
Filed: |
January 06, 2016 |
PCT No.: |
PCT/US2016/012296 |
371(c)(1),(2),(4) Date: |
June 01, 2018 |
PCT
Pub. No.: |
WO2017/119874 |
PCT
Pub. Date: |
July 13, 2017 |
Prior Publication Data
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|
Document
Identifier |
Publication Date |
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US 20180274460 A1 |
Sep 27, 2018 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F02D
19/0634 (20130101); F02D 41/0025 (20130101); F02D
19/087 (20130101); F02D 19/0613 (20130101); F02D
19/0628 (20130101); F02D 19/081 (20130101); G01F
1/84 (20130101); G01F 1/86 (20130101); G01F
1/74 (20130101); Y02T 10/30 (20130101); Y02T
10/00 (20130101) |
Current International
Class: |
F02D
19/08 (20060101); G01F 1/86 (20060101); F02D
41/00 (20060101); G01F 1/84 (20060101); F02D
19/06 (20060101); G01F 1/74 (20060101) |
Foreign Patent Documents
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102007056819 |
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May 2009 |
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DE |
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2532862 |
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Dec 2012 |
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EP |
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2532862 |
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Dec 2012 |
|
EP |
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2007331484 |
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Dec 2007 |
|
JP |
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20140060596 |
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May 2014 |
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KR |
|
2015044334 |
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Apr 2015 |
|
WO |
|
WO2015044334 |
|
Apr 2015 |
|
WO |
|
Primary Examiner: McCall; Eric S.
Assistant Examiner: Graves; Timothy P
Attorney, Agent or Firm: The Ollila Law Group LLC
Claims
We claim:
1. A method of characterizing a mixed fuel flow period, the method
comprising: flowing a mixed fuel during the mixed fuel flow period
when fuel is switched from a first fuel type to a second fuel type;
determining a density of the first fuel type and a density of the
second fuel type; and determining a total flow of the mixed fuel
flow period, the total flow being determined from the density and a
concentration of the first fuel type and the density and a
concentration of the second fuel type.
2. The method of claim 1, further comprising determining a mixed
fuel flow start time and a mixed fuel flow end time.
3. The method of claim 1, further comprising determining a
concentration of the first fuel type and the concentration of the
second fuel type during the mixed fuel flow period.
4. The method of claim 1, further comprising adding the total flow
of the mixed fuel flow period with a total flow of a single fuel
flow of at least one of the first fuel type and the second fuel
type.
5. The method of claim 1, wherein the total flow of the mixed fuel
flow period is comprised of a total flow of at least one of the
first fuel type, the second fuel type, and the mixed fuel flow.
6. The method of claim 1, wherein the mixed fuel flow period is
determined from at least one of a temperature change, a density
change, and a signal associated with the mixed fuel flow.
7. The method of claim 1, wherein the mixed fuel flow period is
comprised of a mixed fuel flow start time and a mixed fuel flow end
time.
8. The method of claim 1, wherein the total flow is comprised of a
total mass flow.
9. A fuel control system (300) for characterizing a mixed fuel flow
period, the system (300) comprising: a first fuel source (312)
having a first fuel type; a second fuel source (314) having a
second fuel type; a flow meter (5) fluidly coupled to the first
fuel source (312) and the second fuel source (314), the flow meter
(5) being configured to measure a mixed fuel flow during a mixed
fuel flow period when fuel is switched from the first fuel type and
the second fuel type and measure a density of the first fuel type
and a density of the second fuel type; and a controller (360)
communicatively coupled to the flow meter (5), the controller (360)
being configured to determine a total flow of the mixed fuel flow
period, the total flow being determined from the density and a
concentration of the first fuel type and the density and a
concentration of the second fuel type.
10. The fuel control system (300) of claim 9, further comprising a
first valve (322) fluidly coupled to the first fuel source (312)
and a second valve (324) fluidly coupled to the second fuel source
(314), the first valve (322) and the second valve (324) being
communicatively coupled to the controller (360).
11. The fuel control system (300) of claim 9, further comprising a
re-circulator (350) fluidly coupled to the flow meter (5) and an
engine (20), the re-circulator (350) being configured to
recirculate unconsumed fuel provided by the engine (20) back to the
engine (20).
12. The fuel control system (300) of claim 9, wherein the
controller (360) is further configured to determine a mixed fuel
flow start time and a mixed fuel flow end time.
13. The fuel control system (300) of claim 9, wherein the
controller (360) is further configured to determine the
concentration of the first fuel type and the concentration of the
second fuel type.
14. The fuel control system (300) of claim 9, wherein the
controller (360) is further configured to add the total flow of the
mixed fuel flow period with a total flow of a single fuel flow of
at least one of the first fuel type and the second fuel type.
15. The fuel control system (300) of claim 9, wherein the total
flow of the mixed fuel flow period is comprised of a total flow of
at least one of the first fuel type, the second fuel type, and the
mixed fuel flow.
16. The fuel control system (300) of claim 9, wherein the mixed
fuel flow period is determined from at least one of a temperature
change, a density change, and a signal associated with the mixed
fuel flow.
17. The fuel control system (300) of claim 9, wherein the mixed
fuel flow period is comprised of a mixed fuel flow start time and a
mixed fuel flow end time.
18. The fuel control system (300) of claim 9, wherein the total
flow is comprised of a total mass flow.
Description
TECHNICAL FIELD
The embodiments described below relate to mixed fuel flows and,
more particularly, to characterizing a mixed fuel flow period.
BACKGROUND
The marine industry uses different grades of fuels for engines in
ships. Although the engines can burn the different fuel grades
using various fuel injection control technology, certain conditions
can limit the fuel grades that may be used. For example,
regulations may limit the fuel grades that can be used by the
engine based on the location of the ship. In one specific example,
ECA zone regulations may require marine gas oil (MGO) be used when
within a range of a coastline. However, MGO may be more expensive
than other fuel grades, such as a heavy fuel oil (HFO) grade.
Accordingly, HFO, and other less expensive grades, may be used when
the ship is not subject to the conditions. For example, HFO may be
used when the ship is greater than a distance from the coastline.
As the ship moves closer to the coastline, fuel control systems may
switch from the HFO to the MGO to meet the ECA zone regulation.
During the fuel switchover, both the HFO and MGO are flowing
through the system as a mixed fuel flow. The time that both the HFO
and MGO are flowing through the fuel control system may be referred
to as a mixed fuel flow period.
The mixed fuel flow period may not be understood. That is, the
concentration, total flow, etc., of the mixed fuel flow may not be
understood. As a result, in the example with the HFO and MGO fuel
grades, the fuel control system may perform the fuel switchover
prematurely. Due to the premature fuel switchover, the more
expensive MGO grade fuel may be used even though the ship is not
subject to the ECA zone regulations. This unnecessary use of the
MGO grade fuel is a cost that may be avoided if the mixed fuel flow
period is characterized.
SUMMARY
A method of characterizing a mixed fuel flow period is provided.
According to an embodiment, the method comprises flowing a mixed
fuel, the mixed fuel being comprised of at least a first fuel type
and a second fuel type, and determining a density of the first fuel
type and a density of the second fuel type. The method also
comprises determining a total flow, the total flow being determined
from the density of the first fuel type and the density of the
second fuel type.
A fuel control system for characterizing a mixed fuel flow period
is provided. According to an embodiment, the fuel control system
comprises a first fuel source having a first fuel type, a second
fuel source having a second fuel type, and a flow meter fluidly
coupled to the first fuel source and the second fuel source. The
flow meter is configured to measure a density of the first fuel
type and a density of the second fuel type. The fuel control system
also comprises a controller communicatively coupled to the flow
meter. The controller is configured to determine a total flow, the
total flow being determined from the density of the first fuel type
and the density of the second fuel type.
Aspects
According to an aspect, a method of characterizing a mixed fuel
flow period comprises flowing a mixed fuel, the mixed fuel being
comprised of at least a first fuel type and a second fuel type,
determining a density of the first fuel type and a density of the
second fuel type, and determining a total flow, the total flow
being determined from the density of the first fuel type and the
density of the second fuel type.
Preferably, the method further comprises determining a mixed fuel
flow start time and a mixed fuel flow end time.
Preferably, the method further comprises determining a
concentration of the first fuel type and a concentration of the
second fuel type during the mixed fuel flow period.
Preferably, the method further comprises adding the total flow
during the mixed fuel flow with a total flow of a single fuel flow
of at least one of the first fuel type and the second fuel
type.
Preferably, the total flow is comprised of a total flow of at least
one of the first fuel type, the second fuel type, and the mixed
fuel flow.
Preferably, the mixed fuel flow period is determined from at least
one of a temperature change, a density change, and a signal
associated with the mixed fuel flow.
Preferably, the mixed fuel flow period is comprised of a mixed fuel
flow start time and a mixed fuel flow end time.
Preferably, the total flow is comprised of a total mass flow.
According to an aspect, a fuel control system (300) for
characterizing a mixed fuel flow period comprises a first fuel
source (312) having a first fuel type, a second fuel source (314)
having a second fuel type, a flow meter (5) fluidly coupled to the
first fuel source (312) and the second fuel source (314), the flow
meter (5) being configured to measure a density of the first fuel
type and a density of the second fuel type, and a controller (360)
communicatively coupled to the flow meter (5), the controller (360)
being configured to determine a total flow, the total flow being
determined from the density of the first fuel type and the density
of the second fuel type.
Preferably, the fuel control system (300) further comprises a first
valve (322) fluidly coupled to the first fuel source (312) and a
second valve (324) fluidly coupled to the second fuel source (314),
the first valve (322) and the second valve (324) being
communicatively coupled to the controller (360).
Preferably, the fuel control system (300) further comprises a
re-circulator (350) fluidly coupled to the flow meter (5) and an
engine (20), the re-circulator (350) being configured to
recirculate unconsumed fuel provided by the engine (20) back to the
engine (20).
Preferably, the controller (360) is further configured to determine
a mixed fuel flow start time and a mixed fuel flow end time.
Preferably, the controller (360) is further configured to determine
a concentration of the first fuel type and a concentration of the
second fuel type.
Preferably, the controller (360) is further configured to add the
total flow with a total flow of a single fuel flow of at least one
of the first fuel type and the second fuel type.
Preferably, the total flow is comprised of a total flow of at least
one of the first fuel type, the second fuel type, and the mixed
fuel flow.
Preferably, the mixed fuel flow period is determined from at least
one of a temperature change, a density change, and a signal
associated with the mixed fuel flow.
Preferably, the mixed fuel flow period is comprised of a mixed fuel
flow start time and a mixed fuel flow end time.
Preferably, the total flow is comprised of a total mass flow.
BRIEF DESCRIPTION OF THE DRAWINGS
The same reference number represents the same element on all
drawings. It should be understood that the drawings are not
necessarily to scale.
FIG. 1 shows a fuel control system 100 for characterizing a mixed
fuel flow period.
FIG. 2 shows another fuel control system 200 for characterizing a
mixed fuel flow period.
FIG. 3 shows another fuel control system 300 for characterizing a
mixed fuel flow period.
FIG. 4 shows a graph 400 illustrating a temperature of a fuel flow
during a mixed fuel flow period.
FIG. 5 shows a table 500 characterizing a mixed fuel flow.
FIG. 6 shows a method 600 of characterizing a mixed fuel flow
period.
DETAILED DESCRIPTION
FIGS. 1-6 and the following description depict specific examples to
teach those skilled in the art how to make and use the best mode of
embodiments of characterizing a mixed fuel flow period. For the
purpose of teaching inventive principles, some conventional aspects
have been simplified or omitted. Those skilled in the art will
appreciate variations from these examples that fall within the
scope of the present description. Those skilled in the art will
appreciate that the features described below can be combined in
various ways to form multiple variations of characterizing the
mixed fuel flow period. As a result, the embodiments described
below are not limited to the specific examples described below, but
only by the claims and their equivalents.
The mixed fuel flow period may be characterized by determining
densities of a first and second fuel type in the mixed fuel flow.
Concentrations, such as percentage or volume, of the first and
second fuel type may be determined from the densities of the first
and second fuel type. Other properties or characteristics of the
mixed fuel flow may also be determined, such as the temperature,
flow rates, etc. Changes in these properties or signals associated
with the mixed fuel flow, such as commands to valves that control a
supply of the first and second fuel type, may be used to measure
the mixed fuel flow period. For example, changes in the temperature
and density of the mixed fuel flow may indicate a start and/or end
time of the mixed fuel flow period.
Using the densities of the first and second fuel type, a total flow
of the mixed fuel flow may be determined. By knowing the total flow
of, for example, the first fuel type through a fuel control system,
the fuel control system may perform an optimal fuel switchover. For
example, when a ship approaches a region requiring the fuel
switchover, the time of the fuel switchover can be determined based
on the characteristics of the mixed fuel flow period. That is, the
fuel switchover may occur such that the first fuel type is
sufficiently consumed by the time the ship enters the region.
Accordingly, a more expensive grade of fuel may not be used until
required, thereby reducing fuel costs, as the following discusses
in more detail.
Fuel Control System
FIG. 1 shows a fuel control system 100 for characterizing a mixed
fuel flow period. As shown in FIG. 1, the fuel control system 100
is comprised of a flow meter 5 fluidly coupled to an engine 20.
Also shown is a re-circulator 150, which is comprised of a fuel
line conveying unconsumed fuel provided by the engine 20. The
re-circulator 150 re-circulates the unconsumed fuel back to the
engine 20 to be consumed. The flow meter 5 is fluidly coupled to
the engine 20 via the re-circulator 150.
As shown in FIG. 1, the flow meter 5 may be a vibratory flow meter,
such as a Coriolis flow meter, although any suitable flow meter may
be employed in alternative embodiments. The flow meter 5 may be
configured to measure and/or determine properties and
characteristics of the fuel flowing through the flow meter 5. For
example, the flow meter 5 may measure a density of the fuel flowing
through the flow meter 5. Accordingly, the flow meter 5 may measure
the density of the first and second fuel type when the first and
second fuel type are flowing through the flow meter 5. The flow
meter 5 may also determine the flow rate, such as a mass or volume
flow rate, of the fuel. The flow meter 5 may also be configured to
measure a temperature of the fuel.
Although the flow meter 5 is shown as a single integrated unit, the
flow meter 5 may be comprised of separate components distributed
throughout the fuel control system 100. For example, a meter
electronics in the flow meter 5 may be part of a separate
controller that is communicatively coupled to, for example, the
engine 20. Additionally or alternatively, the flow meter 5 may be
comprised of separate components that perform specific functions,
such as a first component that measures the density of the fuel, a
second component that measures the flow rate, etc. The flow meter 5
may also be disposed at different locations in the fuel control
system 100. For example, the flow meter 5 may be disposed closer to
the engine 20, be part of the re-circulator 150, etc.
As shown in FIG. 1, the flow meter 5 receives fuel from a fuel
source (indicated as an arrow in FIG. 1) and provides the fuel to
the re-circulator 150. The fuel provided by the flow meter 5 is
mixed with the unconsumed fuel provided by the engine 20 into a
re-mixed fuel. As can be appreciated, the flow meter 5 provides
fuel to the re-circulator 150 at a rate that may be similar to a
rate of consumption by the engine 20. As can also be appreciated,
FIG. 1 shows a serial configuration. That is, only one flow meter 5
is employed to provide the fuel to the engine 20. In addition, the
rate of consumption by the engine 20 is determined from the flow
meter 5. Other configurations may be employed, as the following
discussion illustrates.
FIG. 2 shows another fuel control system 200 for characterizing a
mixed fuel flow period. As shown in FIG. 2, the fuel control system
200 is comprised of inlet flow meters Si fluidly coupled to engines
20. The return flow meters 5r are also fluidly coupled to the
engines 20. Also shown is a re-circulator 250, which is comprised
of a fuel line re-circulating unconsumed fuel provided by the
engine 20. The re-circulator 250 conveys the re-circulated fuel
back to the engine 20 to be consumed. The inlet flow meters Si are
fluidly coupled to the engine 20 and the return flow meters 5r are
fluidly coupled to inlet flow meters Si via the re-circulator 250.
The inlet and return flow meters Si, 5r may be the same as the flow
meter 5 described with reference to FIG. 1.
The inlet flow meters Si receive fuel from a fuel source (indicated
as an arrow in FIG. 2) and provide the fuel to the engines 20. The
fuel provided by the inlet flow meters Si is mixed with the
unconsumed fuel provided by the engines 20 into a re-mixed fuel. As
can be appreciated, the inlet flow meters Si provide the re-mixed
fuel to the engines 20 at a rate that may be similar to a rate of
consumption by the engines 20. The rate of consumption by the
engines 20 may also be similar to the difference in flow rates
measured by the inlet flow meters 5i and the return flow meters 5r.
As can also be appreciated, FIG. 2 shows a parallel configuration
of the inlet flow meters 5i, engines 20, and return flow meters
5r.
The fuel control systems 100, 200 described in the foregoing may
have a single fuel flow or a mixed fuel flow. More specifically,
the fuel sources indicated by the arrows may be comprised of a
single fuel type or a mixture of fuel types. For example, the
single fuel type may be one of the HFO and MGO and the mixture of
fuel types may include both the HFO and MGO. Accordingly, the mixed
fuel flow may include the HFO and MGO. The mixed fuel flow may
occur during a mixed fuel flow period, which may be a fuel
switchover, which is discussed in more detail in the following.
FIG. 3 shows another fuel control system 300 for characterizing a
mixed fuel flow period. As shown in FIG. 3, the fuel control system
300 is comprised of fuel sources 310 fluidly coupled to valves 320.
The valves 320 are fluidly coupled to a first mixer 330, which is
configured to receive and mix fuel supplied via the valves 320. The
first mixer 330 is fluidly coupled to the flow meter 5 shown in
FIG. 3, and is configured to supply fuel from the first and/or
second fuel source 312, 314. The flow meter 5 is configured to
receive and measure properties of the supplied fuel. The flow meter
5 is fluidly coupled to a second mixer 340. The second mixer 340 is
also fluidly coupled to the engine 20 and a re-circulator 350. The
second mixer 340 and re-circulator 350 are fluidly coupled to the
engine 20. The second mixer 340 is configured to receive and mix
the supplied fuel provided by the flow meter 5 and re-circulated
fuel from the re-circulator 350 into a re-mixed fuel, and provide
the re-mixed fuel to the engine 20. The flow meter 5, engine 20,
fuel sources 310, valves 320, and re-circulator 350 are
communicatively coupled to a controller 360.
The fuel sources 310 are comprised of a first fuel source 312 and a
second fuel source 314. The first fuel source 312 may be a tank
(e.g., day tank) with a first fuel type appropriate for a first set
of conditions. For example, the first fuel type may be appropriate
for use in regions with less restrictive regulations. In one
example, the first fuel type may be HFO, although any suitable fuel
type may be provided by the first fuel source 312. The second fuel
source 314 may also be a tank with a second fuel type that is
appropriate for a second set of conditions. For example, the second
fuel type may be appropriate for use in regions with more
restrictive regulations. In one example, the second fuel type may
be MGO, although any suitable fuel type may be provided by the
second fuel source 314.
As shown, the valves 320 are comprised of a first valve 322 and a
second valve 324, which are respectively fluidly coupled to the
first and second fuel source 312, 314. The first and second valve
322, 324 may be fuel switchover valves controlled by the controller
360. The first and second valve 322, 324 may be the same or
different size, include sub-controllers, sensors, such as position
sensors, or the like. The first and second valve 322, 324 are
disposed proximate the first and second fuel source 312, 314 and
away from the first mixer 330. However, in alternative embodiments,
the first and second valve 322, 324 may be disposed away from the
first and second fuel source 312, 314.
By being disposed proximate the first and second fuel source 312,
314, a volume of the supplied fuel between the first and second
fuel source 312, 314 and the first and second valve 322, 324 may
not be substantial. When, in alternative embodiments, the first and
second valve 322, 324 are disposed away from the first and second
fuel source 312, 314 and proximate the first mixer 330, the volume
of fuel between the first and second valve 322, 324 may be
substantial. Similarly, in this alternative embodiment, the volume
of the fuel between the valves 320 and the engine 20 may not be
substantial.
The first and second mixer 330, 340 may be tanks configured to hold
and mix the first and second fuel types into a mixed fuel that is
homogenous. That is, the mixed fuel is uniformly comprised of the
received first and second fuel type. As can be appreciated,
although homogenous, the concentration of the first and second fuel
type may vary over time. The first and second mixer 330, 340 may
rely on various mechanisms to homogenize the fuel. For example, the
first and second mixer 330, 340 may employ, for example,
environmental vibrations, agitators, or the like, to homogenize the
fuel. However, any suitable configuration may be employed in
alternative embodiments.
The re-circulator 350 may be configured to condition fuel
re-circulated by the engine 20 for consumption by the engine 20.
The re-circulator 350 may be comprised of a pressure controller,
temperature controller, or the like, although any suitable
configuration may be employed. Conditioning the fuel re-circulated
by the engine 20 may include the controller 360 controlling the
pressure, temperature, etc., such that the re-circulated fuel is
suitable for use by the engine 20. However, in alternative
embodiments, the fuel reconditioning may include utilizing
components that are not controlled by the controller 360.
The controller 360 may be a circuit board that includes a processor
communicatively coupled to a memory and I/O ports, although any
suitable controller may be employed in alternative embodiments. The
controller 360 may include software that executes methods, such as
the methods described herein, to control the flow of fuel through
the fuel control system 300 shown in FIG. 3. The software may be
stored in the memory and executed by the processor in the
controller 360. Although the controller 360 is described as being a
single circuit board, in alternative embodiments, other controllers
may be comprised of two or more boards, such as sub-boards,
modules, or the like.
As shown, the controller 360 may be configured to communicate with
the flow meter 5, engine 20, valves 320, and re-circulator 350
using the I/O ports. The I/O ports may be configured to communicate
using any appropriate communication means, such as, for example,
serial, parallel, packet-based, etc. The controller 360 may
receive, for example, flow rate measurements from the flow meter 5,
fuel consumption data from the engine 20, valve position
information from the valves 320, and fuel re-circulation data from
the re-circulator 350 via the I/O ports. The controller 360 may
also send commands, such as valve open/close commands, to the
valves 320 and fuel conditioning commands to the re-circulator
350.
The processor in the controller 360 may use the received flow rate
data to calculate a flow rate of the mixed fuel flowing through the
flow meter 5. The processor in the controller 360 may be also
configured to determine a mixed fuel consumption rate using flow
rate of the mixed fuel provided by the flow meter 5. The processor
in the controller 360 may also send commands to open and close the
valves 320 over the I/O ports. The commands may be sent
simultaneously or at different times. The controller 360 may also
include a timer used by the processor to determine the time that
the commands are sent to the first and/or second valve 322,
324.
Although not shown in FIG. 3, the fuel control system 300 may be
comprised of additional components, such as temperature or pressure
sensors, flow control valves, pressure regulators, or the like.
Alternatively, other embodiments may not employ all of the
components shown in FIG. 3. For example, the other embodiments may
not employ the first and second mixer 330, 340, re-circulator 350,
etc. Additionally or alternatively, the components shown in FIG. 3
may have other configurations. For example, the first and second
mixer 330, 340 may include sensors and/or actuators that are
controlled by the controller 360 to mix the fuel received by the
first and second mixer 330, 340.
As can be appreciated, in the embodiment shown in FIG. 3, the fuel
received by the flow meter 5 may be from the first fuel source 312,
second fuel source 314, or both. If the first valve 322 is open and
the second valve 324 is closed, then the fuel received by the flow
meter 5 may be comprised substantially of the first fuel type. If
the first valve 322 is closed and the second valve 324 is open,
then the fuel received by the flow meter 5 may be comprised
substantially of the second fuel type. If both the first and second
valve 322, 324 are open, then the fuel received by the flow meter 5
may be a mixed fuel comprised of the first fuel type and the second
fuel type.
The valves 320 may be opened and/or closed at the same or different
times. For example, the valves 320 may be in a state where the
first valve 322 is open and the second valve 324 is closed. This
state may be used when, for example, the engine 20 is being used in
a ship in a region with less restrictive regulations that allow the
use of the first fuel type. When the ship moves to a region with
more restrictive regulations (e.g., ECA zone regulations), the
first valve 322 may close and the second valve 324 may open.
Accordingly, the opening and closing of the first and second valve
322, 324 may occur substantially simultaneously.
As can be appreciated, the first fuel type in the fuel control
system 300 is not immediately consumed by the engine 20 as soon as
the first valve 322 is closed. For example, the first fuel type may
remain between the fuel sources 310 and the engine 20 for a period
of time. In addition, the second fuel type is not immediately
provided to the engine 20 when the second valve 324 is opened. The
second fuel type may need to flow from the second valve 324 to the
engine 20 after the second valve 324 is opened. As a result, both
the first and second fuel type may be between the valves 320 and
the engine 20. Accordingly, in the embodiment, the first fuel type
is mixed with the second fuel type such that a concentration of the
first fuel type decreases over time and a concentration of the
second fuel type increases over time, as the following discussion
with reference to FIG. 4 illustrates.
Mixed Fuel Flow
FIG. 4 shows a graph 400 illustrating a temperature of a fuel flow
during a mixed fuel flow period. As shown in FIG. 4, the graph 400
includes a time axis 410 and a temperature axis 420. Fuel
temperature plots 430 are also shown. The fuel temperature plots
430 are comprised of a first fuel temperature plot 432 and a second
fuel temperature plot 434. The fuel temperature plots 430 traverses
a mixed fuel flow period 440. The mixed fuel flow period 440
includes a mixed fuel flow start time 440a and a mixed fuel flow
end time 440b.
The mixed fuel flow period 440 may be comprised of a fuel flow
switchover time. More specifically, with reference to the fuel
control system 300 shown in FIG. 3, the mixed fuel flow period 440
may be comprised of the time between when the first and second
valve 322, 324 are respectively closed and opened and when the
first fuel type is substantially consumed by the engine 20. As
shown, the mixed fuel flow period 440 is non-zero. That is, the
first fuel type is not immediately consumed by the engine 20. In
addition, the second fuel type is not immediately provided to the
engine 20.
As a result, during the mixed fuel flow period 440 shown in FIG. 4,
a concentration of the first fuel type may trend downwards with a
slope similar to a slope in the first fuel temperature plot 432.
Conversely, a concentration of the second fuel type may trend
upwards with a slope at a rate similar to the downward slope of the
second fuel temperature plot 434. However, other concentrations may
be employed in alternative embodiments. For example, in embodiments
where the first valve 322 is opened and the second valve 324 is
closed, then a concentration of the first fuel type may increase
while a concentration of the second fuel type decreases.
The concentrations of the first and second fuel type in the mixed
fuel may be determined using the following equations (1) and (2):
1=X+Y (1) .rho..sub.total=X*.rho..sub.1+Y*.rho..sub.2 (2)
Where:
X is a concentration of a first fuel type in the mixed fuel;
Y is a concentration of a second fuel type in the mixed fuel;
.rho..sub.1 is a density of the first fuel type;
.rho..sub.2 is a density of the second fuel type; and
.rho..sub.total is the density of the mixed fuel.
As can be appreciated, the densities of the first and second fuel
type .rho..sub.1, .rho..sub.2 may need to be known to solve the
foregoing equations (1) and (2) for the first and second relative
concentration X, Y.
The densities of the first and second fuel type .rho..sub.1,
.rho..sub.2 may be determined in any appropriate manner. For
example, the densities of the first and second fuel type
.rho..sub.1, .rho..sub.2 may be stored in, for example, a meter
electronics in the flow meter 5, the memory in the controller 360,
or the like. In an embodiment, the density of the first fuel type
.rho..sub.1 may be determined prior to the mixed fuel flow period.
That is, the flow meter 5 may measure the density of the first fuel
type .rho..sub.1 while the first fuel type is flowing prior to the
mixed fuel flow period. Accordingly, in this embodiment, the
density of the second fuel type .rho..sub.2 may be measured after
the mixed fuel flow period. As a result, the density of the second
fuel type .rho..sub.2 may not be known until after the mixed fuel
flow period.
The density of the mixed fuel .rho..sub.total may be determined by
using the flow meter 5 shown in FIG. 4. For example, the density of
the mixed fuel .rho..sub.total may be measured by the flow meter 5
while the mixed fuel is flowing through the flow meter 5. As can be
appreciated, the controller 360 can determine the mixed fuel flow
start time 440a and the mixed fuel flow end time 440b by, for
example, storing time data associated with the fuel flow start time
440a and the fuel flow end time 440b. Accordingly, the density of
the mixed fuel .rho..sub.total may be measured and correlated with
the mixed fuel flow period 440.
The concentrations of the first and second fuel X, Y, which may be
percent concentrations, may be solved (e.g., continuously,
discretely, etc.) over a period of time, such as during the mixed
fuel flow period 440. For example, the foregoing equations (1) and
(2) may be solved continuously using the densities of the first and
second fuel type .rho..sub.1, .rho..sub.2. In the example where the
first valve 322 is open and the second valve 324 is closed, the
density of the first fuel type .rho..sub.1 may be determined when
only the first fuel type is flowing through the flow meter 5. Since
the second valve 324 may not be opened until the mixed fuel flow
start time 440a, the density of the second fuel type .rho..sub.2
may not be determined until after the mixed fuel flow end time
440b.
Once the concentrations of the first and second fuel type X, Y are
solved over the period of time, the flow of the first and second
fuel type may be totalized. For example, the foregoing equation (1)
may be integrated over a period of time, such as the mixed fuel
flow period 440, to determine a total (e.g., mass) of each fuel
type consumed by the engine 20. The totalization may also include
fuel flow before and after the mixed fuel flow. The total mass flow
of the first and second fuel type may also be determined by, for
example, using the following third and fourth equation:
M.sub.FuelType1=.intg.X(t)m.sub.totaldt (3)
M.sub.FuelType2=.intg.Y(t)m.sub.totaldt (4) Where: m.sub.total is
the total mass of the mixed fuel consumed during the mixed fuel
flow period; M.sub.FuelType1 is the total mass of the first fuel
type consumed during the mixed fuel flow period; M.sub.FuelType2 is
the total mass of the second fuel type consumed during the mixed
fuel flow period; X(t) is the concentration of the first fuel type
over time; and Y(t) is the concentration of the second fuel type
over time. As can be appreciated, although the foregoing discusses
the mixed fuel flow period 440 being determined where the fuel is
switched from the first fuel type to the second fuel type, the
mixed fuel flow period 440 can be determined when the fuel is
switched from the second fuel type to the first fuel type.
Accordingly, in this alternative embodiment, the mixed fuel flow
period 440 may be determined from a start time on the right side of
the graph 400 and to an end time on the left side of the graph 400.
As can also be appreciated, various methods may be employed to
determine a time period of the mixed fuel flow period.
Determining the Time Period
The various methods that may be employed to determine the time
period of the mixed fuel flow period may include employing density
or temperature changes in the fuel flow, the controller 360 using
signals associated with the mixed fuel flow, such as the controller
360 determining when the commands are sent to open and close the
valves 320, or the like, which are discussed in the following in
more detail. However, other methods may be employed in alternative
embodiments.
Temperature Changes
The method that employs temperature changes in the fuel flow may
determine the mixed fuel flow start time 440a and the mixed fuel
flow end time 440b when the temperature of the fuel flow changes.
Employing the temperature changes in the fuel flow may be comprised
of measuring a temperature of one of the first and second fuel type
during a single fuel flow. The term `single fuel flow` may refer to
a state where the fuel in the fuel control system 300 is
substantially filled with one of the first and second fuel type and
the corresponding one of the first and second valve 322, 324 is
open, although any suitable definition may be employed. For
example, an alternative definition of single fuel flow may refer to
when one of the first and second fuel type is flowing through the
flow meter 5. In these and other embodiments, during the single
fuel flow, the temperature may remain substantially constant.
When the first and second valve 322, 324 are opened and closed
(e.g., simultaneously), then the temperature of the fuel, which may
be a mixed fuel flow, flowing through the fuel control system 300
may change. For example, in a manner similar to that shown in FIG.
3, the temperature of the fuel may trend from the temperature of
one of the fuel types to the other of the fuel types. The mixed
fuel flow start time 440a may be detected when the temperature of
the fuel flow exceeds a temperature threshold. For example, when
the single fuel flow is comprised of the first fuel type, the
controller 360 may track the temperature of the first fuel type
and, using statistical methods, establish the temperature threshold
using, for example, a confidence interval.
Density Changes
The method that employs density changes in the fuel flow may
determine the mixed fuel flow start time 440a and the mixed fuel
flow end time 440b when the density of the fuel flow changes. The
density of the fuel flow may change because the density of the
first fuel type may be different than the density of the second
fuel type. Similar to the method that employs the temperature
changes, employing the density changes in the fuel flow may be
comprised of measuring a density of one of the first and second
fuel type during a single fuel flow. During the single fuel flow,
the density may remain substantially constant.
When the first and second valve 322, 324 are opened and closed
(e.g., simultaneously), then the density of the supplied fuel,
which may be a mixed fuel flow, flowing through the fuel control
system 300 may change. For example, in a manner similar to that
shown in FIG. 4, the density of the fuel may trend from the density
of one to the other of the first and second fuel type. The mixed
fuel flow start time 440a may be detected when the density of the
fuel flow exceeds a density threshold. For example, when the single
fuel flow is comprised of the first fuel type, the controller 360
may track the density of the first fuel type and, using statistical
methods, establish the density threshold using, for example, a
confidence interval.
Signals
As discussed in the foregoing with reference to FIG. 3, the
controller 360 may determine when the commands are sent to open and
close the valves 320. Accordingly, the method that employs signals
associated with the mixed fuel flow, such as the commands to open
and close the valves 320, may determine the mixed fuel flow start
time 440a and the mixed fuel flow end time 440b. Other signals
associated with the mixed fuel flow may be employed, such as, for
example, valve position signals provided to the controller 360 to
indicate if the first and second valve 322, 324 are open or
closed.
In the foregoing methods, the first and second fuel type, as the
single fuel flow or mixed fuel flow, may be throughout the fuel
control system 300. Whether the single fuel flow or mixed fuel flow
is found in a particular location in the fuel control system 300
may depend on the timing of the opening and closing of the first
and second valve 322, 324, as the following discussion with
reference to FIG. 5 illustrates.
Locations of Fuel Types
FIG. 5 shows a table 500 characterizing a mixed fuel flow. The
table 500 includes time rows 510 listing time before the mixed fuel
flow start time ("TIME<0"), a mixed fuel flow start time (shown
as "TIME=START"), and a mixed fuel flow end time (shown as
"TIME=FINAL"). The mixed fuel flow start time and end time may be
the mixed fuel flow start time and end time 440a, 440b described in
the foregoing with reference to FIG. 4. The table 500 also includes
fuel system location columns 520, which are shown as being fuel
sources, re-circulator, and engine. In the table 500 are the first
and second fuel type TYPE 1, TYPE 2, which indicate whether the
first or second fuel type TYPE 1, TYPE 2 are at the locations
indicated in the fuel system location columns 520.
The table 500 shows that before the mixed fuel flow start time
TIME<0, fuel in a fuel control system, such as the fuel control
system 300 described in the foregoing with reference to FIG. 3, may
be a single fuel flow. As shown in FIG. 5, the single fuel flow is
comprised of the first fuel type TYPE 1. With reference to the
embodiment that employs HFO fuel as the first fuel type, the fuel
sources 310 are supplying the HFO fuel. Accordingly, the first
valve 322 may be open and the second valve 324 may be closed. In
addition, the re-circulator 350 may be filled with the HFO fuel.
Similarly, the engine 20 may be consuming the HFO fuel.
Accordingly, the entire fuel control system 300 may be filled with
the first fuel type from the first fuel source 312.
At TIME=START, which is the mixed fuel flow start time, the fuel
sources 310 may be supplying the second fuel type TYPE 2.
Accordingly, the first valve 322 may be closed and the second valve
324 may be open. The re-circulator 350 and engine 20 may be filled
with both the first and second fuel type. In the embodiment where
the second fuel type is MGO fuel, the re-circulator 350 may be
filled with the HFO and MGO fuel. Similarly, the engine 20 may be
consuming the HFO and MGO fuel. Accordingly, a portion of the fuel
control system 300 may be filled with a single fuel flow comprised
of the MGO fuel and another portion of the fuel control system 300
may be filled with a mixed fuel flow comprised of the HFO and MGO
fuel.
At TIME=FINAL, which is the mixed fuel flow end time, the fuel
sources 310 may be supplying the second fuel type TYPE 2.
Accordingly, the first valve 322 may be closed and the second valve
324 may be open. The re-circulator 350 and engine 20 may be filled
with the second fuel type. In the embodiment where the second fuel
type is MGO fuel, the re-circulator 350 may be filled with the MGO
fuel. Similarly, the engine 20 may be consuming the MGO fuel.
Accordingly, the entire fuel control system 300 may be filled with
the second fuel type from the second fuel source 314.
Although the foregoing refers to percent concentrations of the
first and second fuel type TYPE 1, TYPE 2, other concentrations may
be employed. For example, volume concentrations of the first and
second fuel type TYPE 1, TYPE 2 may be determined. The volume
concentrations of the first fuel type TYPE 1 may be determined
using the following equation (5):
##EQU00001## The foregoing equation (5) may be differentiated to
determine a rate of change in the concentration of the first fuel
type. For example, the rate of change in the concentration of the
first fuel type may be determined using the following equation
(6):
.times..times. ##EQU00002## The foregoing equation (6) is a
differential equation that may be integrated with respect to time
to determine the concentration of the first fuel type TYPE 1 as a
function of time. As can be appreciated, integrating the foregoing
equation (6) can result in the following equation (7):
.function. ##EQU00003## Equation (7) may be used as an
approximation for empirically refining a characterization of a
mixed fuel flow period. For example, equation (7) may be used to
refine theoretical solutions for total flow of the mixed fuel flow
based upon known values and parameters such as, for example,
mixture rates, etc. These and other methods may be employed, as the
following discussion with reference to FIG. 6 illustrates.
Method
FIG. 6 shows a method 600 of characterizing a mixed fuel flow
period. As shown in FIG. 6, in step 610, the method 600 begins by
flowing a mixed fuel. The mixed fuel is comprised of at least a
first fuel type and a second fuel type. In step 620, the method 600
determines a density of the first fuel type and the second fuel
type. The first and second fuel type may respectively be HFO and
MGO fuels provided by the first and second fuel source 312, 314
described in the foregoing. In step 630, the method 600 determines
a total flow during the mixed fuel flow period. The total flow is
determined from the density of the first fuel type and the density
of the second fuel type.
In step 610, the method 600 may cause the first and second fuel
source to provide the mixed fuel to the flow meter 5 shown in FIG.
3. The mixed fuel may be provided by opening and closing the valves
320. For example, if the fuel control system 300 has a single fuel
flow comprised of the first fuel type, then the first valve 322 may
be closed and the second valve 324 may be opened, such that the
fuel sources 310 switch from the first fuel type to the second fuel
type. However, the first fuel type may still be present in the fuel
control system 300 shown in FIG. 3. Accordingly, the fuel flowing
through the flow meter 5 may be the mixed fuel flow during the
mixed fuel flow period.
The method 600, in step 620, may employ the flow meter 5 to measure
the densities of the first and second fuel type. The flow meter 5
may measure the density using any appropriate means. The measured
densities may be provided to the controller 360. The controller 360
can use the densities to determine concentrations of the first and
second fuel type. For example, the controller 360 can execute
methods that employ the foregoing equations (1) and (2). However,
the densities can be used to determine any appropriate fluid
property or characteristic.
In step 630, the method 600 may determine the total flow during the
mixed fuel flow period, such as the mixed fuel flow period 440
described in the foregoing. The mixed fuel flow period may be
determined using fluid properties, such as changes in the densities
or temperature of the fuel flow, or the like. The mixed fuel flow
period may also be determined from signals, such as valve open and
close signals, that are sent and/or received by the controller 360.
The total flow determined during the mixed fuel flow period may be,
for example, the total mass flow determined using the
concentrations of the first and second fuel flow using the
foregoing equations (3) and (4).
As explained above, the fuel control system 300 and method 600 can
characterize the mixed fuel flow period 440. The fuel control
system 300 may include the flow meter 5 configured to determine the
density of the first fuel type and the second fuel type in the
mixed fuel flow. Using the densities of the first and second fuel
type, a total flow of the mixed fuel flow may be determined. By
knowing the total flow of, for example, the first fuel type through
the fuel control system 300, the fuel control system 300 may
perform an optimal fuel switchover. For example, when a ship
approaches a region requiring the fuel switchover, the time of the
fuel switchover can be determined based on the characteristics of
the mixed fuel flow. That is, the fuel switchover may occur such
that the first fuel type is sufficiently consumed by the time the
ship enters the region. Accordingly, a more expensive grade of fuel
may not be used until required, thereby reducing fuel costs.
The detailed descriptions of the above embodiments are not
exhaustive descriptions of all embodiments contemplated by the
inventors to be within the scope of the present description.
Indeed, persons skilled in the art will recognize that certain
elements of the above-described embodiments may variously be
combined or eliminated to create further embodiments, and such
further embodiments fall within the scope and teachings of the
present description. It will also be apparent to those of ordinary
skill in the art that the above-described embodiments may be
combined in whole or in part to create additional embodiments
within the scope and teachings of the present description.
Thus, although specific embodiments are described herein for
illustrative purposes, various equivalent modifications are
possible within the scope of the present description, as those
skilled in the relevant art will recognize. The teachings provided
herein can be applied to other systems and methods that
characterize a mixed fuel flow period and not just to the
embodiments described above and shown in the accompanying figures.
Accordingly, the scope of the embodiments described above should be
determined from the following claims.
* * * * *